1. Field of the Invention
This invention relates to synthetic asphalt, and more particularly, to the process for making synthetic asphalt by selectively blending gilsonite with tall oil and/or tall oil pitch.
2. Description of the Prior Art
Asphalt is typically made of petroleum products, and includes two components, asphaltenes, or petroleum resins, and maltenes, or heavy oils. The asphaltenes are generally dispersed and melted in the maltenes or heavy oils. There are two primary factors in the manufacture of petroleum asphalts which generally determine the grade of the asphalts. They are the proportion of asphaltenes to the maltenes and the viscosity of the maltenes.
There are three ways of classifying petroleum asphalts. The first classification is penetration at 25.degree. C., according to ASTM procedures D-5 and D-946. The second classification is asphalt-cement viscosity, or AC grade, according to ASTM procedures D-2171 and D-3381. The third classification is aged residue viscosity after subjecting the asphalt to oxidation in a rolling thin film oven, or AR-grade, according to ASTM procedures D-2872 and D-3381.
The cost of petroleum asphalt, and petroleum base asphalt recycling agents, has risen sharply in the past few years. Current costs cause the repair of existing asphalt roadways and the construction of new asphalt roadways to be rather expensive. It is likely that such costs will continue to rise. The availability of man-made, or synthetic, asphalt mixtures, and synthetic asphalt recycling agents, produced and marketable at lower costs per ton than equivalent petroleum base products, should help relieve some of the prohibitive costs of the petroleum based asphalts.